Optical techniques have previously been suggested for information security [see, for example, Appl. Opt. 32:5026 (1993); Opt. Eng. 33:1752 (1994); Opt. Lett. 20:767 (1995); and Opt. Lett. 23:1483 (1998)]. Encrypted holographic memory systems have previously been demonstrated for retrieving information for authorized users [see Opt. Lett. 24:762 (1999)]. In these systems two random phase masks located at the input and Fourier planes convert an original image into a random-noise-like image. A correct random phase key is required for successful retrieval of the original data. This encrypted holographic memory potentially has a large storage capacity with a fast access; thus it can be used as an encrypted database.
Pulse shapers based on Fourier synthesis in the temporal frequency domain have previously been thoroughly investigated [see, for example, Appl. Phys. B 50:101 (1990); IEEE J. Quantum Electron 28:2251 (1992); Opt. Lett. 19:664 (1994); Appl. Opt. 37:2858 (1998); and J. Opt. Soc. Am. A 16:1076 (1999)]. For secure communications A. W. Weiner et al. [see IEEE J. Quantum Electron 28:2251 (1992)] proposed a technique based on spectral phase coding for encryption and decryption of femtosecond pulses. This technique can be used in a code-division multiple-access network. Pulse shapers (or spatial-temporal converters) can be used to send spatial data to remote users at ultrahigh speeds as great as terabit(s).
It is among the objects of the present invention to provide an ultrafast data communication system that can link remote users to an encrypted database with high security and ultrafast transfer rate.